But imagine being able to print a kidney, or a brand new beating heart. Jennifer Lewis of Harvard University, who runs a team working at the living edge of 3D bioprinting, is aiming to do just that.

What do you see as being the long-term goal of bioprinting?

The ability to print and implant vital organs. Perhaps the first step will be an implanted tissue patch that would augment or repair a damaged organ. But clearly the holy grail would be to engineer vital organs, such as the kidney, the heart, the liver. To do so for those three organs would be of tremendous value. That’s what people are chasing, and what the research group I’m part of is focused on.

How close would you say we are to printing an organ?

We’re still decades away. It’s not enough to just print liver cells or cardiac cells or kidney cells. These cells have to function, they have to mimic the high densities of the living tissue. An organ performs many functions in the body, so we have to be able to replicate all of that and also put it into the body without the body rejecting it. There are so many challenges.

So we are also pursuing goals with immediate impact. As an example, the …